The Israeli military has begun airstrikes against Iran, two U.S. officials said Thursday evening, a dramatic escalation that increased the chances of an all-out war between the countries and expanding the long-running regional conflict.

There is no U.S. involvement or assistance, the officials said.

Israel confirmed it had launched a strike on Iran, and declared a state of emergency early Friday local time.

“Following the State of Israel’s pre-emptive strike against Iran, a missile and drone attack against the State of Israel and its civilian population is expected in the immediate future,” Israel’s Defense Minister Israel Katz said in a statement early Friday local time.

The move appeared to be a significant break with the Trump administration, which has been in talks with Tehran on a possible nuclear deal and argued against such a step.

Israel became more serious about attacking Iran as negotiations between the United States and Iran appeared closer to a preliminary agreement that included provisions about uranium enrichment that Israel views as unacceptable.

A big worry for the U.S. is Iran retaliating against American personnel or assets in the region. Officials earlier announced the voluntary departure of nonessential employees, and the Defense Department announced the voluntary departure of military families from across the U.S. Central Command area of operations.

The Trump administration had ordered all embassies within striking distance of Iran’s missiles, aircraft and other assets (including missions in the Middle East, Northern Africa and Eastern Europe) to send cables with assessments about danger and about measures to mitigate risks to Americans and U.S. infrastructure, two sources told NBC News this week.

Earlier this week, the board of governors of the International Atomic Energy Agency, the United Nations’ nuclear watchdog, formally found that Iran isn’t complying with its nuclear obligations for the first time in 20 years.